local-guru.net

Many hardware synthesizer come with an USB port these days and some of them even
connect as a soundcard, allowing you to route the audio from the synth directly to
your daw without wasting an input on your soundcard. And sometimes you want to record
something using an USB microphone or USB Guitar cable.

To connect such devices to my DAW via jack on linux I created a little startup script that runs
every time I start Bitwig Studio to make sure all the external devices are connected.
I use alsa_in - a command line tool that allows you to connect an additional alsa
sound card. a2jack needs some parameters like the device name, sampling rate or buffer
size to use and starts a process. Then it starts a process that listens to the alsa device
and forwards the input to jack by connecting as a jack client application with some inputports.
These ports can be configured as input routes in your daw like Bitwig or ardor - just like
you would do with an input channel on your main sound-card.

To route audio from your daw to the output of an second sound you can use alsa_out

My music startup script connects the audio interface of my Yamaha MX61 and an usb-soundcard, that is connected to my Korg KaosPad Mini, so I can use
it as an external effects processor in bitwig-studio

You can get a list of the available alsa device names by running the command

aplay -L

Unfortunately the USB soundcard I use always selects the microphone input when it is plugged in or my computer restarts. To fix this I use the amixer command to change the capture channel to line and mute it - so I don' t generate feedback loops (I spent hours finding out where that distortion came from :-/)

Most launchpad videos feature cool effects running on a launchpad. There are several tutorials
on how to make such effects using ableton live. But since my launchpad is connected to a linux box
this doesn´t help me much. So I wrote a short chuck script that reacts to the midi events sent by
the launchpad and creates an arpeggiator effect to light up the leds. The color can be influenced by
changing the velocity.